Three-phase electric motors are frequently used, among other fields, in automotive applications. Some of the applications are safety applications where corresponding systems are required to enter into a fail-safe mode, even if the electronic entity controlling the system is no longer available, for example, when it is damaged and therefore not able to control the system any longer. In the case of the three-phase electric motor which may be used for electric steering in any kind of vehicle, it should still allow to turn the steering wheel in fail-safe mode. With an AC induction motor, i.e. an electric motor in which the magnetic field of the rotor is created by an induced current, this is not an issue. However, when an AC synchronous motor is used, such as a PMSM (permanent magnet synchronous motor), which allows to generate high torque from a compact and light mechanic system, there is the problem that even after the motor is shut down, for example due to a system error, the magnetic moment of the permanent magnet of the still spinning rotor will induce a current in the coils of the stator and, in effect, a torque will act back on the rotor. This may lead to situations in which the motor may be blocked and hence may not be turned. In order to avoid such states of the motor when a PMSM is used, it must be ensured that in fail-safe mode there is no current circulating in the windings of each of the phases. In order to satisfy this requirement, appropriate circuitry needs to be implemented for isolating the phases in a fail-safe mode. In early applications, isolating circuitry was based on mechanical relays. Nowadays, mechanical relays are predominantly replaced with solid state relays in the form of transistors which are arranged between the half bridges of the inverter and the individual phases of the electric motor. However, when solid state relays are used to isolate the phases, a substantial amount of energy which needs to be dissipated to shut off the system has to be dealt with. This energy may prove problematic in the sense that the solid state relays may be damaged in the fail-safe mode or, in order to prevent that from happening, expensive power components may have to be used.